This invention relates to translucent rubber-modified styrene polymers.
There is a need for impact resistant styrene polymers which are translucent or transparent. Impact resistance now is imparted to styrene polymers by polymerizing styrene in the presence of 3 to 10% of various rubber compounds such that discrete rubber-polystyrene phases are incorporated within a styrene homopolymer matrix. Unfortunately for some applications, these rubber-modified styrene polymers usually are opaque. To be commercially acceptable, a suitable translucent impact resistant polystyrene should have a notched Izod value of at least 0.6 foot-pound/inch of notch and a translucency index of at least 7 on a scale from 1 to 10.
One approach to this problem is described in British Pat. No. 1,185,122 which recommends the addition of 0.05 to 2% of .beta.-bromostyrene to the polymerization feedstock in order to produce a transparent rubber-modified polystyrene. However, polymeric compositions produced using the method disclosed in this British Patent can have an undesirable brownish color.
It is an object of this invention to produce an impact resistant translucent styrene polymer. Another object of this invention is to produce such a polymer which is not discolored. Still another object of this invention is to provide brominated rubbers which can be incorporated within a styrene polymerization feedstock providing an impact resistant translucent polymer and which will not corrode a polymerization reactor vessel.